The Mets go for the sweep tonight of the Washington Nationals. The Mets have been in this spot before, on the verge of a sweep against an inferior opponent, but somehow manage to stumble.

The odds of doing so tonight are greatly reduced with Johan Santana pitching. Santana is coming off an emotional victory last Friday over the Boston Red Sox.

Daniel Murphy is back at first base tonight, with Fernando Martinez batting seventh and playing right field.

For as long as Jose Reyes is out, it looks as if Angel Pagan will get the lion’s share of the time as the leadoff hitter whenever he’s in the line-up. Luis Castillo took a few turns there, but manager Jerry Manuel likes him batting second, which I have advocated all along.

Note: Carlos Beltran, who took a cortisone injection in his knee, is on target to return Friday. … Omir Santos was scratched with a bruised shin. … Oliver Perez’s knee is still bothering him. … Four of tonight’s starters weren’t on the Opening Day roster.

Johan Santana is pitching tonight for the Mets against Atlanta, and if the trend continues he’ll get two runs and win. The Mets, going for their eighth straight victory, just can’t score for Santana, giving him a dozen runs in his six starts.

Why can’t the Mets score for Santana? It’s as if they think “all we need is a couple because they won’t score against him.” Not a good mindset to have.

The Mets are on a good roll, but they have to maintain. They can’t afford to let up, especially against the Braves, who have a way of putting the Mets in their place.

The best pitcher in the sport will try to extend the Mets’ winning streak to three games tonight against the Phillies. Johan Santana could easily be 5-0 with a little more support.

Interesting changes in the line-up, beginning with Daniel Murphy batting sixth behind David Wright because Alex Cora gets the start at second. Ryan Church, who is in a dreadful slump and hitting .143 with RISP in on the bench.

The assumption is Johan Santana will pitch well and the Mets should beat the Washington Nationals tonight. That’s always the assumption when the best pitcher in the major leagues faces its worst team.

The Mets come limping back into town losers of four straight games, the last three in St. Louis. The common denominator in the four games was the inability to hit with runners in scoring position and bad starting pitching. The only decent start came last Sunday against Milwaukee by Nelson Figueroa and he’s no longer in the organization.

As a stopper, Santana is expected to pitch well, but let’s not assume all is well with your heroes even should he throw a shutout.

Even should they sweep the Nationals, it won’t mean all is well. They need to go through the rotation two, three times getting solid starts to allay those concerns.

What we have with the 6-9 Mets is a developing trend. It obviously can’t continue at this rate, but even so, that’s still too small a sample to assume they should write off the season.